A vehicle engine may be started (or restarted after an idle stop) using an engine starter. An example of such starters may include a starter motor connected to a starter relay. The starter motor may be mechanically coupled via a drive shaft to a pinion gear which may be moved into a meshing position with a ring gear coupled to an engine crankshaft. During engine cranking, a battery delivers an electric current to the starter motor causing the drive shaft attached to the pinion gear to rotate, and thereby allowing the pinion gear to drive the ring gear. Once in meshing engagement with the pinion gear, the rotary motion of the ring gear causes the engine crankshaft to rotate rapidly, allowing the engine to start.
Other examples of engine starters may include permanently engaged starter (PES) and integrated starter generators (ISG). In PES systems, the pinion gear is permanently meshed with the ring gear, during engine operation. When the pinion gear is permanently engaged with the ring gear for longer periods of time, increased gear wear and high duty cycles may lead to reduced gear lifespan. These systems may require additional sealed lubrication systems. Further, use of high gear ratios (e.g., 10-15:1) between the pinion and ring gear, during engine startup may result in high speeds in the pinion gear which may be destructive. A power converter, typically placed between the engine and transmission, converts mechanical power of the engine into electrical energy when used in ISG systems. Alternatively, the power converter may convert vehicle electrical power into mechanical power. When functioning as an electric motor, the ISG system may be used to start the engine. The ISG system can also function as a generator, producing electric power (when the vehicle is operating), which may be used to power electric devices and charge a vehicle battery. Some ISG systems require high starting torque and may produce large vibrations during engine operation.
An example engine starter for a vehicle is disclosed by Haruno in U.S. Pat. No. 8,754,556. Therein, the engine starter includes a starter relay connected to a battery and a starter motor that is mechanically coupled to a clutch and a pinion gear via a drive shaft. The starter relay has a plunger that is connected to the drive shaft via a shift lever. During engine startup, an electric current from the battery passes through an electromagnetic coil within the starter relay to generate a force that actuates the plunger to move the shift lever. Forward movement of the shift lever shuttles the pinion gear to a meshing position with a ring gear coupled to an engine crankshaft.
However, in the embodiment of the engine starter disclosed above, the pinion gear may be engaged with the ring gear while the vehicle is at rest (i.e., crankshaft speed may be close to zero). Since the pinion gear has to be brought into alignment with the ring gear each time the engine is started, engine startup time may be increased causing unnecessary delays and reduction in fuel economy. Furthermore, backlash may occur when the pinion gear is engaged with the ring gear, causing driver discomfort.
The inventors herein have recognized the various issues discussed above, and developed an engine starter system to at least partially address the issues. In one example, an engine starter system may include a ring gear coupled to an engine crankshaft, and a pinion gear coupled to a starter motor, the pinion gear having centrifugally engaging elements (e.g., rocker elements) that selectively engage with the ring gear. In this way, the pinion gear may engage with the ring gear when the centrifugally engaging elements of the pinion gear rotate from a retracted position to an engaged position, to enable quick engine startup.
For example, the ring gear of the engine starter system may be permanently aligned with the pinion gear. When the engine is started, the rocker elements of the pinion gear may deploy from their pockets, allowing the pinion gear to engage with the ring gear and transmit torque to the engine crankshaft. After the engine has started, the pinion gear may be disengaged from the ring gear and the rocker elements may be rotated to the retracted position. In this way, the vehicle engine may be quickly started to improve fuel efficiency while reducing (e.g., minimizing) gear backlash and increasing the lifespan of gear components.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.